Tapering of Etanercept is feasible in patients with Rheumatoid Arthritis in sustained remission: a pragmatic randomized controlled trial.

OBJECTIVE: In patients with rheumatoid arthritis (RA) in sustained remission, tapering of biological disease-modifying anti-rheumatic drugs can be considered. Tapering has already been investigated, but its feasibility remains to be determined. Therefore, we explored the feasibility of tapering etanercept in RA in a setting close to practice. METHOD: Patients with RA in 28-joint Disease Activity Score (DAS28) remission (≥ 6 months) and treated with etanercept 50 mg weekly (≥ 1 year) were included in the pragmatic 1 year open-label multicentre randomized controlled TapERA (Tapering Etanercept in Rheumatoid Arthritis) trial. Patients were assigned to continue etanercept weekly or to taper to every other week (EOW). Patients who lost remission [DAS28-C-reactive protein (CRP) ≥ 2.6] were re-escalated to etanercept weekly. The primary outcome was the proportion of patients maintaining DAS28-CRP remission for 6 months. RESULTS: Sixty-six patients were randomized to etanercept weekly (n = 34) or EOW (n = 32). After 6 months, 26/34 patients (76%) in the weekly and 19/32 (59%) in the EOW group maintained disease control (p = 0.136). In the EOW group, 20/32 patients (63%) remained on their tapered treatment during the trial. Two patients reintroduced weekly etanercept themselves. Ten patients were re-escalated to etanercept weekly by the rheumatologist, after a median (interquartile range) interval of 3.0 (2.0-6.0) months. Among these patients, 7/10 regained remission after re-escalation, four of them at the next study visit. CONCLUSIONS: Although non-inferiority could not be demonstrated, tapering of etanercept to EOW appeared feasible in patients in sustained remission.

Airborne concentrations and chemical considerations of radioactive ruthenium from an undeclared major nuclear release in 2017.

In October 2017, most European countries reported unique atmospheric detections of aerosol-bound radioruthenium (106Ru). The range of concentrations varied from some tenths of µBq·m-3 to more than 150 mBq·m-3 The widespread detection at such considerable (yet innocuous) levels suggested a considerable release. To compare activity reports of airborne 106Ru with different sampling periods, concentrations were reconstructed based on the most probable plume presence duration at each location. Based on airborne concentration spreading and chemical considerations, it is possible to assume that the release occurred in the Southern Urals region (Russian Federation). The 106Ru age was estimated to be about 2 years. It exhibited highly soluble and less soluble fractions in aqueous media, high radiopurity (lack of concomitant radionuclides), and volatility between 700 and 1,000 °C, thus suggesting a release at an advanced stage in the reprocessing of nuclear fuel. The amount and isotopic characteristics of the radioruthenium release may indicate a context with the production of a large 144Ce source for a neutrino experiment.

Barriers and facilitators to smoking cessation among HIV-infected people who inject drugs (PWID) in Hanoi, Vietnam: a qualitative study.

INTRODUCTION: In Vietnam, 60% of men living with HIV smoke tobacco, and 92% of HIV-infected people who inject drugs (PWID) smoke tobacco. Tobacco use increases mortality through increased health risks including tuberculosis and malignancy in HIV-infected smokers. However, tobacco use treatment is not widely available in Vietnam. The objective was to examine current barriers and facilitators of smoking cessation and tobacco use treatment for HIV-infected PWID in Hanoi, Vietnam. METHODS: Native speaking ethnographers conducted semi-structured qualitative interviews about tobacco use and tobacco use treatment with sixteen HIV-infected PWID and eight healthcare providers, recruited from four HIV-Methadone Maintenance Treatment (MMT) clinics in Hanoi, Vietnam. Interviews were recorded, transcribed, and translated for thematic analysis in Dedoose. RESULTS: Clients and providers had learned the general health risks of smoking from public awareness campaigns. Half had tried to quit previously, often motivated by advice from family members but not by HIV providers' advice. Almost all clients did not want to quit, citing the low price of tobacco, prevalence of smoking in Vietnam, and physical cravings. HIV provider's counseling was brief, inconsistent, and limited by low provider knowledge and competing burdens of HIV and injection drug use. Providers recently trained by NGO-led seminars on tobacco prioritized tobacco use treatment. CONCLUSIONS: Smoking cessation efforts for people living with HIV/AIDS (PLHA) and PWID smokers in Hanoi, Vietnam could benefit from further community public awareness campaigns, and exploring increased tobacco taxation. Tobacco use treatment at HIV clinics could benefit from involving family and friends in cessation, and training providers in treatment methods.

A practical method to account for random phase approximation effects on the dynamic scattering of multi-component polymer systems.

Investigations of polymer systems that rely on the interpretation of dynamical scattering results as, e.g., the structure factor S(Q, t) of single chains or chain sections may require the inclusion of effects, as described within the framework of the random phase approximation (RPA) for polymers. To do this in practice for the dynamic part of S(Q, t) beyond the initial slope is a challenge. Here, we present a method (and software) that allows a straightforward assessment of dynamical RPA effects and inclusion of these in the process/procedures of model fitting. Examples of applications to the interpretation of neutron spin-echo data multi-component polymer melts are shown.

Genetic Diversity and Protective Efficacy of the RTS,S/AS01 Malaria Vaccine.

BACKGROUND: The RTS,S/AS01 vaccine targets the circumsporozoite protein of Plasmodium falciparum and has partial protective efficacy against clinical and severe malaria disease in infants and children. We investigated whether the vaccine efficacy was specific to certain parasite genotypes at the circumsporozoite protein locus. METHODS: We used polymerase chain reaction-based next-generation sequencing of DNA extracted from samples from 4985 participants to survey circumsporozoite protein polymorphisms. We evaluated the effect that polymorphic positions and haplotypic regions within the circumsporozoite protein had on vaccine efficacy against first episodes of clinical malaria within 1 year after vaccination. RESULTS: In the per-protocol group of 4577 RTS,S/AS01-vaccinated participants and 2335 control-vaccinated participants who were 5 to 17 months of age, the 1-year cumulative vaccine efficacy was 50.3% (95% confidence interval [CI], 34.6 to 62.3) against clinical malaria in which parasites matched the vaccine in the entire circumsporozoite protein C-terminal (139 infections), as compared with 33.4% (95% CI, 29.3 to 37.2) against mismatched malaria (1951 infections) (P=0.04 for differential vaccine efficacy). The vaccine efficacy based on the hazard ratio was 62.7% (95% CI, 51.6 to 71.3) against matched infections versus 54.2% (95% CI, 49.9 to 58.1) against mismatched infections (P=0.06). In the group of infants 6 to 12 weeks of age, there was no evidence of differential allele-specific vaccine efficacy. CONCLUSIONS: These results suggest that among children 5 to 17 months of age, the RTS,S vaccine has greater activity against malaria parasites with the matched circumsporozoite protein allele than against mismatched malaria. The overall vaccine efficacy in this age category will depend on the proportion of matched alleles in the local parasite population; in this trial, less than 10% of parasites had matched alleles. (Funded by the National Institutes of Health and others.).

Algorithms for managing infant constipation, colic, regurgitation and cow's milk allergy in formula-fed infants.

UNLABELLED: Gastrointestinal symptoms, such as constipation, regurgitation and infant colic, occur in about half of infants. These symptoms are often functional, but they may also be caused by cow's milk protein allergy. We developed three algorithms for formula-fed infants, which are consensus rather than evidence-based due to the limited research available in the existing literature. CONCLUSION: We believe that these algorithms will help primary healthcare practitioners to recognise and manage these frequent gastrointestinal manifestations in infants.

Interest in multipurpose prevention of HIV and pregnancy: perspectives of women, men, health professionals and community stakeholders in two vaginal gel studies in southern Africa.

OBJECTIVE: The pipeline of vaginal microbicides for HIV prevention has expanded to include products for multipurpose prevention, but the interests of potential users and those advising on use have not been sufficiently investigated. Rather, assumptions about interest in multipurpose prevention technologies (MPTs) are inferred from what is known about acceptability and use of microbicides or contraceptives. DESIGN AND SETTING: This paper presents data on concerns and preferences for multipurpose prevention of HIV and pregnancy. Data were collected in two microbicide gel studies in Malawi and Zimbabwe. Participants were women using candidate vaginal products, their male partners, health professionals and community stakeholders. METHODS: An individual interview was conducted with participants. Interviews were audio-recorded, transcribed, coded for content and analysed for key themes. RESULTS: Participants indicated strong interest in a vaginal HIV prevention product that could also prevent pregnancy. Reasons for this interest were convenience, problems with adverse effects with current contraceptive methods, concerns about long-term effects of contraceptives, and concerns about the health burdens of HIV infection during pregnancy. The main disadvantage of an MPT was recognition that while interest in preventing HIV is constant, contraceptive needs change over time. CONCLUSION: The study population indicated support for an MPT to prevent HIV and pregnancy. This support may be further strengthened if the product is also available for prevention of only HIV. Women and men will be more willing to use an MPT if they can be reassured that its use will have no long-term effect on fertility.

Child with protein losing enteropathy as presentation of collagenous duodenitis and eosinophilic gastroenteritis.

Background: Collagenous duodenitis and gastritis are rare histopathological findings in children. Patients and methods: : We describe a four-year old girl, who presented with non-bloody diarrhea for two months and progressive edema with an albumin of 16g/dl. Results: The diagnosis of a protein losing enteropathy was made. Extensive investigations withheld only an infectious cause of the protein losing enteropathy (cytomegalovirus and adenovirus). However, the patients still required repetitive albumin infusions 3.5 months after onset of symptoms without spontaneous recovery. Therefore, a new endoscopic work-up was performed. Duodenal biopsies revealed collagen deposition, in association with a high number of eosinophils and mast cells throughout different parts of the gastrointestinal tract. Conclusions: The collagen deposition seems to be triggered by an eosinophilic gastrointestinal disorder. Treatment was started with amino acid-based formula, oral iron therapy, an antihistamine, and a proton pomp inhibitor that resulted in persistent normalization of serum albumin already after 1.5 weeks.

Liver abscesses in the Western pediatric population.

Background and study aims: Liver abscesses are rare in the Western pediatric population and data on predisposing factors and etiology are scarce. We aimed to describe predisposing factors, microbiological characteristics, and treatment. Patients and methods: Retrospective analysis of children admitted to two tertiary care hospitals in Belgium from 1 January 1996 to 31 December 2019. We analyzed clinical features, predisposing factors, imaging characteristics, microbiological data, treatment, and outcome in children with a liver abscess and compared these data with the literature. Results: We collected 24 cases with a male to female ratio of 1.4 and a median age of 3.2 years at time of diagnosis. Survival was 95.8%. Invasive culture specimens were obtained in 83.3% and showed growth of bacteria in 55%. Parenteral antibiotics were administered before invasive culture sampling in 80%. Liver abscesses were cryptogenic in four (16.7%) patients. Hepatobiliary disease was the most prevalent predisposing factor (n = 6; 25%), followed by recent antineoplastic therapy for malignancies (n = 5; 20.8%), intra-abdominal surgical pathology (n = 4; 16.7%) and umbilical venous catheters (n = 2; 8.3%). In two patients there was a parasitic origin (n = 2; 8.3%) and in one it was caused by Bartonellosis. There was no diagnosis of chronic granulomatous disease (CGD) in our cohort. Conclusions: Pediatric liver abscesses have a favorable outcome in the developed world. Whenever feasible, invasive abscess culture specimens should be obtained. In patients presenting with a cryptogenic liver abscess or atypical disease course, immunological workup should be ensured.

Can medical residency keep young specialists in the place where they graduate? Cross-sectional and exploratory study of the first seven years after implementation of medical residency programs in the State of Tocantins, Brazil.

BACKGROUND: New medical schools and new medical residencies in Brazil, mainly in its interior, were opened under the justification of collaborating towards distribution of these healthcare professionals and specialist doctors across the national territory. However, this proposal did not guarantee that medical practitioners would become established in the place where they graduated and specialized. OBJECTIVE: To calculate, through interviews, how many specialists who graduated in the state of Tocantins stayed there after finishing their medical residency; and to analyze the factors that made them stay or leave the place. DESIGN AND SETTING: Cross-sectional exploratory study conducted at a Brazilian federal public higher education institution. METHODS: All graduates from medical residencies in Tocantins, who graduated between 2013 and 2019, were contacted by telephone and, after obtaining consent, an interview was conducted. The interviews took place between June 2020 and January 2021. RESULTS: The permanence of medical residency graduates in the state increased from 50% in an earlier study to 55.8% in the current study, thus showing a situation of stability. In addition, we detected some reasons for staying or not. In a multivariate analysis, only working in the state capital was related to staying in the state of Tocantins, showing a 5.6 times greater chance. CONCLUSIONS: The percentage of those who remained was just over 50%, even some years after implementation of the first programs. Most specialists remained working for the state health department, with a smaller proportion in municipal health departments, and were concentrated in the state capital.

Quantitating the multiplicity of infection with human immunodeficiency virus type 1 subtype C reveals a non-poisson distribution of transmitted variants.

Identifying the specific genetic characteristics of successfully transmitted variants may prove central to the development of effective vaccine and microbicide interventions. Although human immunodeficiency virus transmission is associated with a population bottleneck, the extent to which different factors influence the diversity of transmitted viruses is unclear. We estimate here the number of transmitted variants in 69 heterosexual men and women with primary subtype C infections. From 1,505 env sequences obtained using a single genome amplification approach we show that 78% of infections involved single variant transmission and 22% involved multiple variant transmissions (median of 3). We found evidence for mutations selected for cytotoxic-T-lymphocyte or antibody escape and a high prevalence of recombination in individuals infected with multiple variants representing another potential escape pathway in these individuals. In a combined analysis of 171 subtype B and C transmission events, we found that infection with more than one variant does not follow a Poisson distribution, indicating that transmission of individual virions cannot be seen as independent events, each occurring with low probability. While most transmissions resulted from a single infectious unit, multiple variant transmissions represent a significant fraction of transmission events, suggesting that there may be important mechanistic differences between these groups that are not yet understood.

Long-term outcome of treatment with infliximab in 614 patients with Crohn's disease: results from a single-centre cohort.

BACKGROUND AND AIMS: This observational study assessed the long-term clinical benefit of infliximab (IFX) in 614 consecutive patients with Crohn's disease (CD) from a single centre during a median follow-up of 55 months (interquartile range (IQR) 27-83). METHODS: The primary analysis looked at the proportion of patients with initial response to IFX who had sustained clinical benefit at the end of follow-up. The long-term effects of IFX on the course of CD as reflected by the rate of surgery and hospitalisations and need for corticosteroids were also analysed. RESULTS: 10.9% of patients were primary non-responders to IFX. Sustained benefit was observed in 347 of the 547 patients (63.4%) receiving long-term treatment. In 68.3% of these, treatment with IFX was ongoing and in 31.7% IFX was stopped, with the patient being in remission. Seventy patients (12.8%) had to stop IFX due to side effects and 118 (21.6%) due to loss of response. Although the yearly drop-out rates of IFX in patients with episodic (10.7%) and scheduled treatment (7.1%) were similar, the need for hospitalisations and surgery decreased less in the episodic than in the scheduled group. Steroid discontinuation also occurred in a higher proportion of patients in the scheduled group than in the episodic group. CONCLUSIONS: In this large real-life cohort of patients with CD, long-term treatment with IFX was very efficacious to maintain improvement during a median follow-up of almost 5 years and changed disease outcome by decreasing the rate of hospitalisations and surgery.

Juvenile-onset systemic lupus erythematosus: different clinical and serological pattern than adult-onset systemic lupus erythematosus.

OBJECTIVE: To investigate differences in clinical signs and symptoms, and in antinuclear antibodies (ANA), between patients with juvenile-onset and adult-onset systemic lupus erythematosus (SLE). METHODS: Clinical and serological data of 56 patients with juvenile-onset SLE were compared with data of 194 patients with adult-onset SLE. ANA were determined by line immunoassay and by indirect immunofluorescence on Crithidia luciliae. RESULTS: Renal involvement, encephalopathy and haemolytic anaemia were seen, and anti-dsDNA, anti-ribosomal P and antihistone antibodies found, significantly more often in juvenile-onset SLE. Anti-dsDNA antibodies were directly associated, and anti-ribosomal P antibodies inversely associated, with renal involvement in juvenile-onset SLE. In juvenile patients with SLE and anti-dsDNA and without anti-ribosomal P antibodies the odds ratio for glomerulonephritis was 9.00; no patients with anti-ribosomal P but without anti-dsDNA had renal involvement. CONCLUSION: Patients with juvenile-onset SLE more often have renal involvement and encephalopathy than patients with adult-onset SLE. Anti-ribosomal P, anti-dsDNA and antihistone antibodies are more often found in patients with juvenile-onset SLE.

Reversible changes in serum immunoglobulin galactosylation during the immune response and treatment of inflammatory autoimmune arthritis.

OBJECTIVES: Improved DNA sequencer-aided fluorophore-assisted carbohydrate electrophoresis (DSA-FACE) technology was used to monitor the changes in the galactosylation status of serum immunoglobulins during the immune response and therapy of autoimmune arthritis. METHODS: Collagen-induced arthritis (CIA) was induced in susceptible DBA/1 mice and the undergalactosylation status (UGS) of serum immunoglobulins was determined using the improved DSA-FACE technology. Prophylactic intravenous tolerisation with type II collagen as well as semitherapeutic treatment with dexamethasone (DEX) were performed and UGS was analysed. Next, the serum immunoglobulin glycosylation profiles of patients with rheumatoid arthritis (RA) and spondyloarthropathy (SpA) were studied and changes in the UGS scores during anti-tumour necrosis factor (TNF)alpha therapy followed. RESULTS: In the longitudinal CIA study, the undergalactosylation state of immunoglobulins was found to be significantly correlated with the clinical arthritis scores. Upon collagen-specific tolerisation as well as glucocorticoid semitherapeutic treatment, improvement of the clinical arthritis scores correlated with decreased levels of UGS. It was also demonstrated that withdrawal of DEX was associated with an increased UGS score. Interestingly, reversibility in the UGS was also shown during treatment of patients with RA and SpA with anti-TNFalpha. CONCLUSIONS: These findings demonstrate that the UGS of serum immunoglobulins changes during the disease course of CIA and that this UGS is inhibited by antigen-specific and antigen-independent treatment procedures. The observation that Ig galactosylation is a reversible process is also documented during treatment of patients with RA and SpA with anti-TNFalpha.

Sensitivity and specificity of criteria for spondyloarthritis in children with late onset pauciarticular juvenile chronic arthritis as well as their characteristics.

OBJECTIVE: To evaluate the sensitivity and specificity of criteria designed for spondyloarthritis in a university hospital treated population of children with late onset pauciarticular juvenile chronic arthritis and a control population. METHODS: Four sets of criteria especially designed for juvenile patients: Garmisch-Partenkirchen juvenile spondylitis criteria (= Garmisch), SEA (=seronegative enthesopathy and arthritis) syndrome, Enthesitis Related Arthritis (ERA), Atypical spondyloarthritis for children and two sets of criteria for patients without age specification (European spondyloarthropathy Study Group - ESSG and Amor) were evaluated in a cross-sectional way in a group of 43 consecutive patients with late onset pauciarticular juvenile chronic arthritis (LOPA) seen over a six-month period in the outpatient clinic. These criteria were analysed in 69 patients with other forms of juvenile chronic arthritis as well. The sensitivity and specificity were calculated for each set, as well as positive predictive value and likelihood ratio. The characteristics described in the different sets of criteria were separately evaluated in the LOPA patients and the other patients. RESULTS: For sensitivity, the Garmisch criteria scored the highest value (97.7%). However, sensitivity was significantly lower in two of the juvenile sets (SEA syndrome and Atypical spondyloarthritis), respectively 44.2% and 51.2%, as opposed to the other criteria (>85%; p<0.01 by Mc Nemar test). Specificity and positive predictive value (PPV) was the highest for the SEA syndrome criteria (98.5%, vs. 95.0%) followed by the ERA (95.6 % vs. 92.1 %) and the Garmisch criteria (94.2% vs. 91.3%). The positive likelihood ratio (LR+) was >10 in SEA (30.5), ERA (18.7) and Garmisch (16.8). The negative likelihood ratio (LR-) was <0.1 only in the Garmisch criteria (0.02). CONCLUSION: Sensitivity, specificity, PPV, LR+ and LR- for the Garmisch-Partenkirchen criteria suggest that they classify almost the same population as defined by LOPA. The SEA syndrome criteria, which were not designed to be classification criteria, being very specific, cannot be used in this patient population to classify a sufficient number of patients. The sensitivity and specificity for the ESSG criteria being similar in these children as in adults suggest they have similar characteristics. The Garmisch-Partenkirchen criteria and/or LOPA definition are major candidates for future research in identifying spondyloarthritis in juvenile patients.

Identification of a novel PEX14 mutation in Zellweger syndrome.

BACKGROUND: Peroxisome biogenesis disorders are a clinically and genetically heterogeneous group of very severe autosomal recessive disorders caused by impaired peroxisome biogenesis. The prototype of this group of disorders is the cerebro-hepato-renal syndrome of Zellweger. METHODS AND RESULTS: Here we report a patient with Zellweger syndrome, who presented at the age of 3 months with icterus, dystrophy, axial hypotonia, facial dysmorphy, posterior embryotoxon, and hepatomegaly. Abnormal findings of metabolic screening tests included hyperbilirubinaemia, hypoketotic dicarboxylic aciduria, increased C(26:0) and decreased C(22:0) plasma levels, and strongly reduced plasmalogen concentrations. In fibroblasts, both peroxisomal alpha- and beta-oxidation were impaired. Liver histology revealed bile duct paucity, cholestasis, arterial hyperplasia, very small branches of the vena portae, and parenchymatic destruction. Immunocytochemical analysis of cultured fibroblasts demonstrated that the cells contain peroxisomal remnants lacking apparent matrix protein content and PEX14, a central membrane component of the peroxisomal matrix protein import machinery. Transfection of fibroblasts with a plasmid coding for wild-type PEX14 restored peroxisomal matrix protein import, indicating that the primary genetic defect affecting the patient is indeed linked to PEX14. Mutational analysis of this gene revealed a genomic deletion leading to the deletion of exon 3 from the coding DNA (c.85-?_170+?del) and a concomitant change of the reading frame (p.[Ile29_Lys56del;Gly57GlyfsX2]). CONCLUSIONS: This report represents the second PEX14-deficiency associated with Zellweger syndrome and the first documentation of a PEX14-deficient patient with detailed clinical follow-up and biochemical, morphological, and radiological data.

Hypertension in pregnancy among HIV-infected women in sub-Saharan Africa: prevalence and infant outcomes.

This analysis was performed to determine the prevalence of hypertension and association of MAP (mean arterial pressure) with birth outcomes among HIV-infected pregnant women not taking antiretrovirals. HIV-infected pregnant women, enrolled into the HPTN024 trial in Tanzania, Malawi and Zambia were followed up at 26-30, 36 weeks, and delivery. The prevalence of hypertension was <1% at both 20-24 weeks and 26-30 weeks and 1.7% by 36 weeks. A 5 mm Hg elevation in MAP increased the risk of stillbirth at 20-24 weeks by 29% (p = 0.001), 32% (p = 0.001) at 26-30 weeks and of low birth weight (LBW) at 36 weeks by 26% (p = 0.001). MAP was not associated with stillbirth at 36 weeks, LBW prior to 36 weeks, preterm birth, neonatal mortality or the risk of maternal to child transmission (MTCT) of HIV.

The implementation of environmental health policies in health care facilities: The case of Malawi.

Establishing and maintaining safe and sufficient environmental health (EH) conditions in health care facilities (HCFs) is important to prevent and control infections. In 2018, the Government of Malawi finalized an environmental health policy that defines specific targets and programs for EH in healthcare settings. This and other related policies have been used since 2010 as a guide for EH practice in HCFs, but the implementation of these policies has been incomplete to-date. This study qualitatively examines the successes and shortcomings of implementing these policies in Malawi's public HCFs. Thematic analysis of interviews with 53 respondents from all levels of government was used to identify the successes of the policies and the barriers to effective implementation using Contextual Interaction Theory. The greatest identified strength lies in the design of the EH department and its ability to connect individual HCFs and EH actors directly to the policy-making level of government. Identified barriers to implementation include: insufficient financial support; lack of human resources; incomplete reporting; poor stakeholder coordination; and insufficient training of EH actors. We recommend refresher trainings for all EH actors, the establishment of a directorate level EH position, and strengthened coordination to improve the collection, analysis, and reporting of monitoring data to enable EH actors to advocate for the additional funding needed to develop programs for EH personnel and to apply effective EH interventions.

Statistical analysis of uncertainties of gamma-peak identification and area calculation in particulate air-filter environment radionuclide measurements using the results of a Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) organized intercomparison, Part I: assessment of reliability and uncertainties of isotope detection and energy precision using artificial spiked test spectra, Part II: assessment of the true type I error rate and the quality of peak area estimators in relation to type II errors using large numbers of natural spectra.

In this paper, the uncertainties of gamma-ray small peak analysis have been examined. As the intensity of a gamma-ray peak approaches its detection decision limit, derived parameters such as centroid channel energy, peak area, peak area uncertainty, baseline determination, and peak significance are statistically sensitive. The intercomparison exercise organized by the CTBTO provided an excellent opportunity for this to be studied. Near background levels, the false-positive and false-negative peak identification frequencies in artificial test spectra have been compared to statistically predictable limiting values. In addition, naturally occurring radon progeny were used to compare observed variance against nominal uncertainties. The results infer that the applied fit algorithms do not always represent the best estimator. Understanding the statistically predicted peak-finding limit is important for data evaluation and analysis assessment. Furthermore, these results are useful to optimize analytical procedures to achieve the best results.

Measurement and modelling of radioxenon plumes in the Ottawa Valley.

Since 2001 a real-time radiation monitoring network of Canadian nuclear facilities and major population centres has been implemented for response to nuclear incidents including a possible terrorist attack. Unshielded NaI(Tl) spectroscopic detectors are employed to measure gamma radiation from airborne radioactivity and radioactivity deposited on the ground. These detectors are composed of a standard 3''x3'' cylindrical NaI(Tl) spectrometers with data storage and integrated telemetry. Some of the detectors have been deployed in the Ottawa Valley near Chalk River Laboratories and Ottawa, which has a complex radioxenon environment due to the proximity of nuclear power reactors, and medical isotope facilities. Although not a health threat, these releases have provided an opportunity for the Canadian Meteorological Centre and the Commissariat à l'Energie Atomique to validate their meteorological models. The meteorological models of the two organizations are in good agreement on the origin and the source terms of these releases.